The present invention comprises an apparatus for applying a liquid coating to a workpiece, particularly an irregularly shaped workpiece. Although the apparatus could be used to apply many different types of coatings, e.g. paints, rust resistant coatings, oils, etc., it is particularly useful where the coating is something such as paint. While the apparatus could apply such a coating to any irregularly shaped workpiece, it is particularly useful for applying such coatings to elongate workpieces, and even more specifically, to workpieces such as joists or trusses or other elongated structural members, which are comprised of a number of interconnected components such as struts and beams, with open spaces therebetween. With such structures, it is difficult to completely coat all sides of the numerous components which make up the elongate members, and particularly to ensure that the coating gets into all the crevices, recesses and the like formed in and between those components, in a quick, preferably automated, operation.
Dip tanks might appear to be an obvious way of painting such complex, irregular structures. However, they are undesirable because more environmentally friendly, water-based paints do not work well in dip-type applications, and thus organic-based paints must be used. Organic-based paints, especially in dip tanks having openings large enough to introduce a workpiece such as a joist or truss, pose an environmental problem, since undesirably large volumes of hazardous organics can evaporate into the surrounding environment. Accordingly, workers must wear protective clothing, and the area must be ventilated. Even then, undesirable amounts of organic vapors are often released into the atmosphere. Additionally, dipped type structures tend to leave paint drippings in the surrounding locations to the dip tanks, on trucks being loaded with the workpieces, etc.